// retrieve last ref number in the refline from original transaction table
$sql = "SELECT MAX(CAST(SUBSTR($ref_fld, ".(strlen($prefix)+1).",LENGTH($ref_fld)-".(strlen($postfix)+strlen($prefix)).") AS UNSIGNED))"
// retrieve last ref number in the refline from original transaction table
$sql = "SELECT MAX(CAST(SUBSTR($ref_fld, ".(strlen($prefix)+1).",LENGTH($ref_fld)-".(strlen($postfix)+strlen($prefix)).") AS UNSIGNED))"